A more extreme case of hat hair. Helmet hair is a condition where a person's cranial hair appears severly matted to the point where you can make out the contour of the their skull. The hair is usually oily or soaked in sweat. There is no adverse effects to helmet hair other than general repulsion by other human beings.

The cure for helmet hair is a highly technical procedure that most people can learn at home. Most medical circles refer to this procedure as "wet, lather, rinse, repeat".